This invention relates to electric motor starter-generators and, more particularly, to an electric starter-generator system for an aircraft engine having a motor drive that controls two starter-generators coupled to the aircraft engine.
Vehicles, such as aircraft, utilize an electric starter-generator system to start a gas turbine engine. The electric starter-generator system provides torque to the engine to rotate the engine from a zero speed to a speed that is appropriate for starting the engine. Conventional starter-generator systems may include two or more starter-generators that are coupled to the engine to provide a relatively large amount of torque necessary to spool-up the engine. In a starter mode, the starter-generators rotate the jet engine. In a generate mode, the starter-generators convert mechanical energy from rotation of the jet engine into electrical energy for the aircraft.
Typically, each of the starter-generator systems includes a motor drive, such as a motor drive inverter, that powers and individually controls the respective starter-generator in the starter mode. Each motor drive controls the speed and torque output of the respective starter-generator independently from the other motor drive during operation. Disadvantageously, utilizing a motor drive for each starter-generator adds size, expense, and weight to the electric engine starter assembly.
Accordingly, there is a need for an electric starter-generator system having a single motor drive that controls multiple starter-generators to reduce the size, weight, and expense of the electric starter-generator system.